1. The electrochemical properties of membranes made of poly (vinylferrocene-alt-maleic anhydride) and poly (styrene-alt-maleic andhydride) derivatized with ferrocenylmethanol were investigated. The formal redox potentials were found to be dependent upon the pH of the supporting electrolyte solution ph 2-5), the degree of crosslinking with tetraethylene glycol, and the ferrocene content in the membrane, demonstrating their potential use in controlled membrane mediation.2. Photoinduced intramolecular electron transfer and charge separation were examined in polymers derivatized with ruthenium trisbipyridyl and an electron acceptor/relay, diquat. A high concentration of an electron donor, e. g. triethanolamine, was found to be necessary to suppress back electron transfer. Under such conditions diquat reduction by photoreduced ruthenium trisbipyridyl was found to proceed. When the polymer membrane was prepared, inserted between methyl viologen and triethanolamine solutions, and irradiated, mediation via reduced diquat was suggested to occur to effect energetically uphill redox reaction between the two substrates.3. Photoreduction of copper (II) tetrasulphophthalocyanine (CuPcTS) dispersed in polymer matrices was investigated under ultraviolet irradiation. CuPcTS dispersed in poly (vinyl alcohol) was also examined for photoinduced cross-membrane mediation of redox reaction between triethanolamine and methyl viologen. Irradiation from the side of methyl viologen solution was found to give an efficiency of the redox reaction ca. three times higher, as compared with irradiation from the side of triethanol solution. The above finding, together with the results obtained in solution, suggests that CuPcTS in a higher excited state transfers electron to methyl viologen in a so-called oxidative mechanism at the membrane/methyl viologen solution interface.